Thioguanine comes as a tablet to take by mouth usually once a day. The length of treatment depends on the types of drugs you are taking, how well your body responds to them, and the type of cancer you have. Take thioguanine at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take thioguanine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Your doctor may increase or decrease your dose of thioguanine during your treatment. This depends on how well the medication works for you and on the side effects that you experience. Talk to your doctor about how you are feeling during your treatment. Continue to take thioguanine even if you feel well. Do not stop taking thioguanine without talking to your doctor

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Other uses for this medicine

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What special precautions should I follow?

Before taking thioguanine,

  • tell your doctor and pharmacist if you are allergic to thioguanine, any other medications, or any of the ingredients in thioguanine tablets. Ask your pharmacist for a list of the ingredients.
  • tell your doctor if you have already taken thioguanine or mercaptopurine to treat your cancer. Your doctor may tell you not to take thioguanine if either of these medications did not work well against your cancer in the past.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: aminosalicylates such as mesalamine (Apriso, Asacol, Pentasa, others), olsalazine (Dipentum), and sulfasalazine (Azulfidine). Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Also tell your doctor and pharmacist about all the medications you are taking so they can check whether any of your medications may increase the risk that you will develop liver damage during your treatment with thioguanine.
  • tell your doctor if you have or have ever had liver disease.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. You should not become pregnant or breast-feed while you are receiving thioguanine. If you become pregnant while receiving thioguanine, call your doctor. Thioguanine may harm the fetus.
  • do not have any vaccinations without talking to your doctor.
  • you should know that the risk that you will develop serious side effects of thioguanine may be higher if you have a genetic (inherited) risk factor. Your doctor may order tests before or during your treatment to see if you have this risk factor.

What special dietary instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

Drink plenty of fluids during your treatment with thioguanine.

What should I do if I forget a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What should I know about storage and disposal of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.